Recreational vehicle roofing system

ABSTRACT

A method of roofing an occupancy structure comprising providing a roofing membrane that comprises at least one thermoplastic membrane layer, bonding the roofing membrane to the roof of an occupancy structure, where the occupancy structure includes a roof member that is at least partially constructed of a plastic material and extends above the roofing membrane when the roofing membrane is applied to the occupancy structure. A substantially solid hot melt thermoplastic sealant is heated to enable the substantially solid hot melt thermoplastic sealant to flow and a layer of the substantially solid hot melt thermoplastic sealant is applied to an exterior surface of the thermoplastic membrane layer and a plastic portion of the roof member to seal the joint between the roofing membrane and the roof member.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.12/042,693, filed Mar. 5, 2008, which claims priority of U.S.provisional application Ser. No. 60/904,930 filed Mar. 5, 2007, byMerryman et al. for RECREATIONAL VEHICLE ROOFING SYSTEM, which are bothhereby incorporated herein by reference in their entireties.

FIELD AND BACKGROUND OF THE INVENTION

The present invention is directed to a roofing system for a mobileoccupancy structure. In particular, the present invention is directed toa roofing membrane and a sealant for roofing a mobile occupancystructure.

Various types of mobile occupancy structures are provided with roofingmembranes applied as part of the roof construction of the occupancystructure to form a protective layer against harmful weather. Theroofing membranes form a barrier to moisture, such as rain and snow, aswell as provide protection from damaging sun rays. Mobile occupancystructures to which such roofing membranes are applied includerecreational vehicles, such as trailers and motor homes, mobile homes,and trailers for use as temporary offices and classrooms, or the like.

The mobile occupancy structures typically include various roof membersor roof penetrations extending upwards from the roof or mounted to themobile occupancy structure. Roof members may include, for example,vents, air conditioning units, skylights, antennas, and ladders, as wellas flash caps mounted to the upper edges of the occupancy structureadjacent the roof. In the case of upward projecting roof members, theroofing membranes must include apertures or openings to enable the roofmembers to pass through the roofing membrane. To prevent moisture fromleaking past the roofing membrane at the apertures or joints the roofmust be sealed, such as by a sealant applied proximate the apertures orjoints of the roof member and the roofing membrane. Current roofingmembranes for mobile occupancy structures include the rubber compoundethylene propylene diene terpolymer (EPDM), as well as thermoplasticpolyolefin (TPO), with current sealants used with these roofingmembranes including solvent based sealants.

SUMMARY OF THE INVENTION

The present invention provides a roofing system for a mobile occupancystructure, including a roofing membrane formed from or includingthermoplastic vulcanizate (TPV) material. The roofing system may alsoemploy, or alternatively employ, a substantially solid sealant or a highsolid sealant having a high percentage of solids that may be compatiblyformulated for sealing about the roof members while inhibiting shrinkageand cracking associated with sealant curing. In particular embodiments,the roofing membrane and/or substantially solid sealant are compatiblyformulated with polymer bonding additives for promoting adhesion betweenthe roofing membrane and sealant, thus improving the bond between theroofing membrane and sealant.

According to an embodiment of the invention a mobile occupancy roofingsystem comprises a roofing membrane affixed to the roof substrate of amobile occupancy structure, with the roofing membrane including at leastone thermoplastic vulcanizate (TPV) membrane layer. The mobile occupancystructure includes a roof member joined thereto with a sealant disposedon and adhering to the roofing membrane and roof member. The TPVmembrane layer may include a TPV polymer bonding additive and thesealant may include a sealant polymer bonding additive, with the TPVpolymer bonding additive and sealant polymer bonding additiveinteracting to promote adhesion of the sealant with the TPV membranelayer. The sealant may be a substantially solid sealant comprising atleast approximately 90% solids by weight, and may even be 100% solids byweight, prior to being applied to the mobile occupancy structure. Thesubstantially solid sealant may comprise a hot melt sealant.

The TPV polymer bonding additive and sealant polymer bonding additivemay promote adhesion by mechanical or chemical interaction. Mechanicalinteraction may be a result of polar groups in the TPV polymer bondingadditive and sealant polymer bonding additive, or may result from theTPV polymer bonding additive heat welding with the sealant polymerbonding additive during application of the sealant.

The TPV polymer bonding additive may comprise an ethylene vinyl acetate(EVA) and the sealant polymer bonding additive may comprise an EVA. TheTPV polymer bonding additive may alternatively comprise a thermoplasticpolyolefin (TPO) with the sealant polymer bonding additive comprising aTPO. Alternatively, one of the TPV polymer bonding additive and thesealant polymer bonding additive may comprise a maleic anhydride graftedpolymer (MAH), with the other of the TPV polymer bonding additive andsealant polymer bonding additive comprising a gylcidyl methacrylate(GMA). The TPV polymer bonding additive may alternatively comprise astyrene ethylene butylene styrene (SEBS) and the sealant polymer bondingadditive comprises a SEBS. The TPV polymer bonding additive mayalternatively comprise one selected from the group of anethylene-n-butyl acrylate, an ethylene-methyl acrylate, and an ethylene2-ethyl hexyl acrylate, with the sealant polymer bonding additivecomprising an ethylene vinyl acetate (EVA).

According to another aspect of the present invention, a mobile occupancyroofing system comprises a roofing membrane affixed to the roofsubstrate of a mobile occupancy structure, with a roof member joined tothe mobile occupancy structure and a substantially solid sealantdisposed on and adhering to the roofing membrane and roof member. Thesubstantially solid sealant may comprise at least approximately 90%solids by weight, or even 100% solids by weight, prior to being appliedto the mobile occupancy structure. The substantially solid sealant maycomprise a hot melt sealant. The substantially solid sealant may includea sealant polymer bonding additive that interacts with the roofingmembrane to promote adhesion. The roofing membrane may include at leastone thermoplastic vulcanizate (TPV) membrane layer that includes a TPVpolymer bonding additive, with the TPV polymer bonding additive andsealant polymer bonding additive interacting to promote adhesion of thesubstantially solid sealant with the TPV membrane layer.

According to another aspect of the present invention, a method ofroofing a mobile occupancy structure comprises the steps of providing amobile occupancy structure having a roof substrate, providing a roofingmembrane including at least one thermoplastic vulcanizate (TPV) membranelayer with a TPV polymer bonding additive, and bonding the roofingmembrane to the roof substrate and mounting a roof member to the mobileoccupancy structure. The method further comprises providing asubstantially solid sealant having at least approximately 90% solids byweight and including a sealant polymer bonding additive, and applyingthe substantially solid sealant to the roof member and roofing membranewith the substantially solid sealant adhering to the TPV membrane layerand the TPV polymer bonding additive interacting with the sealantpolymer bonding additive. The substantially solid sealant may comprise ahot melt sealant, and may comprise 100% solids by weight prior to beingapplied to the mobile occupancy structure.

According to still another aspect of the present invention, a mobileoccupancy structure having a roofing system comprises a mobile occupancystructure having a roof substrate, a roofing membrane affixed to theroof substrate, and a roof member affixed to the mobile occupancystructure. A hot melt substantially solid sealant is disposed about theroof member with the heat of the heated substantially solid sealantpromoting bonding between the substantially solid sealant and roofingmembrane. The roofing membrane may include a TPV roofing membrane layer.

In yet a further aspect of the present invention, a method of roofing amobile occupancy structure comprises providing a roofing membrane for amobile occupancy structure having a roof member projecting from a roofof the occupancy structure and applying the roofing membrane to themobile occupancy structure such that the roof member projects throughthe roofing membrane. The method further comprises heating a hot meltsealant and applying the hot melt sealant about the roof member afterheating the hot melt sealant such that the hot melt sealant bonds withthe roofing membrane. The roofing membrane may include at least one TPVmembrane layer with the hot melt sealant bonding to the TPV membranelayer. The TPV membrane layer may include a membrane polymer bondingadditive and the hot melt sealant may include a sealant polymer bondingadditive.

The TPV roofing membrane incorporates both elastic and plastic typeproperties to provide the roofing membrane with the flexibility ofrubber and the processing of plastic. As such, the TPV roofing membraneis readily formed and applied to occupancy structures having roofs withmultiple curves or radiuses and is well adapted to provide goodweathering characteristics. In addition, the TPV roofing membraneprovides desirable strength and stretch characteristics such that it maybe installed to an occupancy structure without the inclusion of areinforcement layer and is heat weldable. In addition, the sealant orsealant system of the present invention, which may be used with a TPVroofing membrane or another roofing membrane, such as an EPDM or TPOroofing membrane, enables use of a substantially solid sealant formed ofat least approximately 90% or more solids. The substantially solidsealant and roofing membrane may be compatibly formulated by theinclusion of a polymer bonding additive to avoid the need forapplication of a primer to the roofing membrane while inhibitingshrinkage of the sealant during curing and the associated problems ofcracking and poor adhesion while promoting sufficient bonding of thesealant to the disparate materials of the roofing membrane and roofmembers.

These and other objects, advantages, purposes and features of thisinvention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an occupancy structure in the form of arecreational vehicle trailer having a roof system in accordance with thepresent invention;

FIG. 2 is an enlarged perspective view of a roof member vent of thetrailer of FIG. 1;

FIG. 3 is a perspective view of a roll of TPV roofing membrane inaccordance with the present invention;

FIG. 3A is a partial side elevation view of the TPV roofing membrane ofFIG. 3;

FIG. 4 is a partial side elevation view of an alternative TPV roofingmembrane in accordance with the present invention;

FIG. 4A is a partial side elevation view of a modified TPV roofingmembrane of FIG. 4 disclosing the inclusion of a reinforcement layer;

FIG. 5 is a partial side elevation view of another alternative TPVroofing membrane in accordance with the present invention;

FIG. 6 is a partial side elevation view of another alternative TPVroofing membrane in accordance with the present invention;

FIG. 7 is a perspective view of an occupancy structure prior toapplication of a roofing membrane;

FIGS. 8 and 9 are perspective views of the occupancy structure of FIG. 7to which adhesive is being applied to the roof;

FIG. 10 is a perspective view of the application of a roofing membraneto the occupancy structure of FIG. 7; and

FIG. 11 is a perspective view of the occupancy structure to which theroofing membrane has been applied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with reference to theaccompanying figures, wherein the numbered elements in the followingwritten description correspond to like-numbered elements in the figures.

FIG. 1 discloses a movable occupancy structure configured as a trailer20 incorporating a roofing system or sealing system in accordance withthe present invention. Trailer 20 includes a roof 22 covered with aroofing membrane 24, which in the illustrated embodiment is constructedof a thermoplastic vulcanizate (TPV) material. Various roof membersextend from roof 22 through apertures in TPV roofing membrane 24,including a vent 28, an air conditioning unit 30, a skylight 32, and aladder 34. Other roof members include flashing caps, such as sideflashing caps 33 and end flashing caps 35 (front flashing cap notshown). The flashing caps 33, 35 extend onto the roof 22 and at leastpartially down the sides of trailer 20. The roofing system of trailer 20also includes a sealant disposed about the roof members, such as sealant38 disposed about vent 28 (FIG. 2). Sealant 38 bonds to the TPV roofingmembrane 24 and roof members to inhibit moisture from leaking past theroofing membrane 24 at the apertures through which the roof membersextend or at the joint of flashing cap 33, 35 roof members with TPVroofing membrane 24. In the illustrated embodiment sealant 38 is asubstantially solid sealant. In particular embodiments of the roofingsystem, TPV roofing membrane 24 and/or sealant 38 are formulated toinclude polymer sealant bonding additives promoting bonding between theroofing membrane 24 and sealant 38, and/or promoting bonding with theroofing members.

TPV roofing membrane 24 may be readily formed and applied to a movableoccupancy structure having a roof with multiple curves or radiuses, suchas roof 22, and is well adapted to provide good weatheringcharacteristics. Further, as described below, TPV roofing membrane 24has sufficient tensile set properties of strength and stretchcharacteristics such that it may be installed to trailer 20 without theinclusion of a reinforcement layer. Still further, TPV roofing membrane24 has thermoplastic characteristics such that it is heat weldable andmay be readily reworked if required and/or may be processed with heatsealing operations. In addition, scrap trimmings of TPV roofing membrane24 may be re-used or recycled in the production of TPV roofing membrane24. Thus, TPV roofing membrane 24 has both elastic and plasticproperties giving it the feel of rubber and the processing of plastic.

As best seen in FIG. 2, sealant 38 is disposed about conventional flange36 of vent 28 extending from roof 22 through roofing membrane 24, suchthat sealant 38 adheres to both flange 36 and roofing membrane 24.Although not shown, sealant 38 is likewise disposed about the other roofmembers, including air conditioning unit 30, skylight 32, ladder 34, andat the joints formed with flashing caps 33, 35, and may be disposedabout or adjacent other roof members that are not shown, such asantennas, many of which roof members may also include flanges that arelikewise not shown. Sealant 38, thus, adheres to such roof members androofing membrane to provide a moisture barrier.

In the illustrated embodiment, as also described in more detail below,sealant 38 is a substantially solid sealant or high solid sealant formedof at least approximately 90-100% solids to inhibit shrinkage of thesealant 38 during curing and the associated problems of shrinkage andadhesion, such as may occur with solvent based sealants. Still further,as also discussed below, due to the selected formulation of sealant 38and TPV roofing membrane 24 to be compatible, sealant 38 maysufficiently bond to TPV roofing membrane 24 without the need to primeTPV roofing membrane 24 prior to application of sealant, therebypromoting sufficient bonding of the sealant to both the disparatematerials of the roofing membrane 24 and roof members.

Referring to FIG. 3, a roll 40 of TPV roofing membrane 24 may be usedduring construction of a movable occupancy structure. Roll 40 may beapproximately 114 inches wide by 450 feet long and, as described in moredetail below, is unrolled and adhered to the roof of a movable occupancystructure during construction thereof. It should be understood thatalternative rolls of roofing membrane may be utilized, such as forexample with alternatively sized occupancy structures.

The TPV compound for producing TPV roofing membrane 24 can be producedin thermoplastic equipment and does not require a post cure process asdoes rubber. The TPV compound may, for example, be produced in a banburymixer, a twin screw extruder, or other medium to high intensity mixers.In the case of a twin screw extruder, the base ingredients for formingthe TPV membrane are added in the feed throat with the exception of aportion of the oil and the curative. Intense mixing then occurs duringthe beginning of the process. Subsequently, the curative is added at apoint where the mixture temperature has been increased to approximately425 degrees Fahrenheit. The TPV material may be formed directly intorolls at a sheeting process, or may alternatively be pelletized andsubsequently formed into sheeting at a separate sheeting process.

The TPV compound is made up of a rubber phase that is crosslinked, withthe crosslinked rubber dispersed in a plastic phase. Raw materials maybe added to the TPV compound, such as oil as an extender, fillers, acurative package, and a stabilization package. The TPV will also havethe positive attributes of TPO that can be processed easily inthermoplastic equipment not requiring a post cure process as in rubber.

The base polymer or rubber phase for the TPV compound may be chosen fromEPDM, Butyl, Neoprene, Epichlorohydrin, Chlorosulfinated polyethylene(CSPE), or other such base polymers, with the base polymer being used,at least in part, to obtain the desired physical properties, discussedbelow, and weathering characteristics. The rubber polymer may also beblended to improve or provide additional properties, such as chemicalresistance or improved adhesion. The plastic phase may be chosen frompolypropylene, polyethylene, or co-polymers of polypropylene andpolyethylene. Fillers may be talc, mica, clay, calcium carbonate, or thelike. Curatives can be either phenolic resin or peroxide. With aphenolic resin cure a halogen donor would be needed and may be stannouschloride or even come from a polymer used in the formulation.Stabilizers may include UV stabilizers and antioxidants.

In general, the maximum or minimum property limits for TPV roofingmembrane 24 may be approximately in the following ranges:

TABLE 1 Tensile strength, min (psi)  900-1100 Elongation, min (%)200-300 Tear resistance, min (lbf/in)  40-150 Tensile set, max % 20-10Brittleness point, max (° F.) (−35)-(−45) Weathering (pass) (hours)6000-8000

It should be appreciated, however, that a TPV roofing membrane may beconstructed with alternative or superior properties than those shownabove and still function as intended. For example, a TPV roofingmembrane could have a tensile strength of approximately 1,800 psi and/ora maximum percentage tensile set of under 10%.

A TPV roofing membrane having a tensile set of less than approximately10% may enable the TPV roofing membrane to be constructed without areinforcement layer. A roofing membrane that does not include areinforcement layer is advantageous for several reasons. For example,elimination of the reinforcement layer saves money and decreases theprocessing difficulty, as well as enables the roofing membrane to retainsufficient flexibility to conform to the broad array of contour that maybe associated with the roof deck surface of a movable occupancystructure.

The following table provides a compound listing in approximate parts perhundred rubber (PHR) and by approximate weight percentage of oneparticular formulation for a TPV suitable roofing membrane.

TABLE 2 PHR Wt. % EPDM 100 29.3 Polypropylene 55 16.1 Processing oil123.8 36.3 Phenolic resin 5.9 1.7 Stannous Chloride 1.5 0.4 Zinc Oxide2.0 0.6 Filler 40 11.7 Titanium Dioxide 11 3.2 Antioxidant 0.4 0.1 UVstabilizer 1.8 0.5

It should be appreciated that differing characteristics, properties,styles, relative amounts, or forms of the above noted compounds, or evenadditional or alternative compounds, may be employed within the scope ofthe present invention. For example, a pigment such as ultramarine bluemay be added, such as in an approximate amount of 0.1 weight percent, toobtain whiter formulations of TPV roofing membranes. Likewise, methylacrylate monomers in conjunction with peroxides may be employed to aidcuring. Further, the EPDM polymer can come in different viscosities,diene types and ethylene propylene ratio. Suppliers of EPDM may includeExxonMobil, the DSM company of the Netherlands, the Chemtura (Crompton)Corp. of Connecticut, Enichem S.p.A. of Italy, and others. EPDM, as wellas phenolic resin, may be obtained extended in oil, in which case thepercent oil in which they are supplied should be subtracted from thetotal oil. Similarly, if other products are supplied extended in oil,the percent oil should also be subtracted from the total oil. Theprocessing oil can vary by viscosity, color and type, such as parafinic,napthenic, or aromatic. Suppliers of processing oil may includeExxonMobil, Sunoco Inc., Citgo, and others.

Similarly, polypropylene of differing crytallinities, melt flows,hardness and copolymer types may be used. Polypropylene may be suppliedby Exxonmobil, Sunoco, the Basell company of the Netherlands, andothers. As previously noted, polyethylene may be used instead of or incombination with polypropylene. Phenolic resin may be supplied indifferent melt points, methylol content and could even be oil extended.The Schnectady (SI Group) of New York, as well as others, may supplyphenolic resin. Stannous chloride may be supplied in either a hydrate oranhydrous form, with the anhydrous form being preferred. Suppliers ofstannous chloride include Arkema of France, J.T. Baker of New Jersey,and others. Zinc oxide is used in the crosslinking of the rubber and maybe supplied, for example, by Harwick Standard, of Akron, Ohio.

Numerous types of filler for the TPV roofing membrane may be employedincluding, for example, talc, mica, clay, calcium carbonate, and silica.The filler may also be of different types, particle sizes and surfacecoatings.

In the illustrated embodiment, titanium dioxide is used as a coloringpigment to create a white formulation. However, other pigments may usedor added to the titanium dioxide or in place of the titanium dioxide fordifferent coloring, with the pigments preferably being of exterior gradedue to ultraviolet (UV) exposure. For exterior applications light colorswill result in cooler internal temperatures for a movable occupancystructure. In addition, the antioxidants and UV stabilizers may besupplied in many forms from numerous suppliers. For example,antioxidants may include hindered phenols, amines, and others, and theUV stabilizers may include hindered amine light stabilizers HATS,hindered amine light stabilizers that have an end group to reduce thebasic nature NOR-HALS, benzophenones, or benzotriazoles. Among others,suppliers of antioxidants include CIBA and suppliers of UV stabilizersinclude CIBA and Cytec.

The above noted formulation is based on a phenolic resin cure system.Alternatively, however, different curative systems such as peroxidecures may be employed. Furthermore, different halogen donors may be usedin lieu of stannous chloride such as, for example, neoprene rubber oranother halogen donor, which may add improved bonding properties to theTPV roofing membrane.

Still further, as described in more detail below, additional oralternative properties and/or characteristics of the TPV roofingmembrane may be obtained by adding functional polymers to the matrixeither as a post add or as a replacement before the curing reaction.Such functional polymers may include chlorine containing maleic ahydridegrafts, acrylics, or arcylate/methyl acrylate monomers. This may providemore reactive sights to which the sealant may bond.

It should also be understood, however, that TPV roofing membranes havingdiffering formulations and/or differing weight percentages may bedevised and function as intended within the scope of the presentinvention. Such differing formulations may, for example, be constructedto obtain different desired properties, such as appearance, performance,or installation properties. For example, the below table illustratesalternative weight percentages by ranges of the above noted componentsthat may be used in creating alternative TPV roofing membranes.

TABLE 3 Approximate Wt. % range EPDM 25-35 Polypropylene 10-25Processing oil 23-43 Phenolic resin 1-3 Stannous Chloride 0.2-0.7 ZincOxide 0.3-0.8 Filler 0.0-25  Titanium Dioxide 0.0-10  Antioxidant 0.0-0.25 UV stabilizer 0.0-1.5

Still further, other alternatives may include a peroxide cure employedin place of the phenolic resin and stannous chloride combination.

Constructing alternative TPV roofing membranes formed from varyingformulations of the above or other compounds with sufficient tensile setcharacteristics, as well as tensile strength and elongation properties,may advantageously enable the TPV roofing membrane to be applied to anoccupancy structure without the need for a reinforcement layer, which inturn may enable additional processing and cost advantages.

Referring again to FIGS. 1 and 2, and as previously noted, substantiallysolid sealant 38 is applied about roofing members to inhibit moisturefrom passing TPV roofing membrane 24 at the apertures through which theroofing members extend, or at the joints formed between the roof membersand roofing membranes, to thereby prevent damage to the roof 22 of themobile occupancy structure. In the illustrated embodiment substantiallysolid sealant 38 is formed of 100% solids. Alternatively, asubstantially solid sealant for sealing an occupancy structure roofingmembrane may be formed of approximately 90% or more solids, such as forexample approximately 95 to 98% solids. The solids portion of thesubstantially solid sealant is that portion that does not evaporate,including processing oil. Some amount of flow of the substantially solidsealant 38 is required during application of sealant 38 to mobileoccupancy structure 20.

It should be appreciated that the greater the percentage of solids, thelower the percentage of solvents and, thus, the amount of solventevaporation. The reduction of solvent evaporation promotes a reductionin shrinkage of the sealant, which aids in preventing unwanted crackingof the solid portion of the sealant left behind after evaporation.Typically such cracks form at the transition between the roofingmembrane and the flange of a roof member that is being sealed. Suchcracking may provide leak paths for moisture to pass by the sealant anddamage the roof 22 of the mobile occupancy structure 20. Reducingshrinkage promotes adhesion of sealant 38 to the roof members androofing membrane 24 as sealant shrinkage may cause a sealant to pullaway from a roof member and/or roofing membrane to which it has beenapplied. Still further, the reduction of solvents reduces solventevaporation, which in turn reduces the hazardous air pollutants (HAP)and volatile organic compounds (VOC) generated during production ofmobile occupancy structures. In solvent based sealants, the solventenables the sealant to flow during application. After application of thesealant, the solvent is released or evaporates. Solvents employed mayinclude toluene, xylene, naptha, mineral spirits, ketones, hexane, andheptane, amongst others.

Substantially solid sealants may be developed as a single component, twocomponent or a hot melt systems, and may include sealant types such asurethanes and/or silicones. Single and two component sealants may becomprised of polyurethane, silicones, modified silicone (MS) polymer,polysulfide, epoxy, acrylic, or the like. A single component sealant maybe configured to cure upon contact with moisture and a two componentsystem may be configured to cure upon mixing of the two componentstogether. Hot melt systems, which are heated and cure upon cooling, mayrange from ethylene vinyl acetate (EVA), thermoplastic olefin (TPO),polyolefin plastomers, amorphous polyalpha olefins (APAO), blockcopolymers such as styrene isoprene styrene (SIS), styrene butylenestyrene (SBS), styrene ethylene butylene styrene (SEBS), styreneethylenepropylene styrene (SEPS), or the like. Hot melt systems may alsocomprise propylene, ethylene, butyl rubber, chlorosulfonatedpolyethylene, ethylene proplylene rubber EPR, ethylene propylene dieneterpolymer (EPDM), polyisobutylene (PIB), or the like.

Substantially solid sealants may be formed in a high speed mixer orreactor, or may be formed in a sigma blade mixer or a twin screwextruder, with the particular type of substantially solid sealantdetermining the type of equipment being used to manufacture the sealant.Production equipment for producing a hot melt substantially solidsealant may require a heated jacket to reach the required temperature toenable mixing. Reactive type substantially solid sealants may requirethe presence of an inert gas in the tank during mixing and packagingoperations. The substantially solid sealant requires a viscositysufficient to enable the sealant to be applied using sealant applicationequipment. For example, substantially solid sealants being applied atroom temperature may have a viscosity range between 50,000 to 2,000,000centipoise, and hot melt substantially solid sealants may have aviscosity range between 2,000 and 1,500,000 centipoise at 350 degreesFahrenheit.

The substantially solid sealant requires good adhesion to the roofingmembrane, as well as to metals and plastics, such as which the flange ofa roof member may be formed. This can be accomplished with the use oftackifying resins and the polymer sealant bonding additive.Substantially solid sealants also require excellent oxidation and UVresistance, which may be obtained using antioxidants and UV stabilizers.Some pigments affecting the opacity of the sealant may also aid in UVresistance, such as titanium dioxide or carbon black. The sealant alsoneeds to be resistant to water, which is achieved by the selection ofthe polymer and other ingredients. The service temperature mustwithstand minus 20 degrees Fahrenheit to 160 degrees Fahrenheit. The lowend of the range can be adjusted by the polymer chosen for the sealantor by adding plasticizers, such as paraffinic oil or polybutene, thatwill lower the glass transition temperature. The selection of thesecomponents must be balanced to maintain the upper service temperature,which an be affected by the selected polymer, the amount of plasticizer,and the melt point of tackifying resin, or any olefin waxes that may beused. Fillers may be used to aid drying of the sealant so that it is nottacky. The substantially solid sealant may be non-sagging or selfleveling depending upon application and customer requirements. Thesealants may be made non-sagging by the addition of thixotropes.

Although described herein in reference to mobile occupancy structures,the substantially solid sealants of the present invention may also beutilized in roofing structures other than mobile occupancy structures,such as stationary commercial buildings.

In particular embodiments, a TPV roofing membrane 24 and/or asubstantially solid sealant 38 may be formulated to include particularpolymer sealant bonding additives to promote bonding or adhesion betweenthe roofing membrane 24 and sealant 38. That is, a substantially solidsealant and a TPV roofing membrane are formulated in a compatible mannerto promote adhesion there between. Compatible formulations of TPVroofing membranes and substantially solid sealants enable the sealantsto bond to the TPV roofing membrane and a roofing member without havingto first apply a primer to the TPV roofing membrane. Specifically, asealing system with cooperatively formulated substantially solid sealantand TPV roofing membrane formulations enables the sealant to be appliedwithout a primer on the roofing membrane while ensuring a sufficientbond with the roofing membrane and roofing member to inhibit theformation of leaks about the roof members. The sealant polymer bondingadditive may comprise the base polymer of the substantially solidsealant, or may be a separate polymer bonding additive depending on theparticular TPV polymer bonding additive of the TPV roofing membrane towhich the substantially solid sealant will be adhered.

For example, the TPV roofing membrane and substantially solid sealantmay be formulated or modified with compatible polymers to increase theadhesion of the substantially solid sealant with the roofing membrane.This may include adding or adjusting functional groups in the TPVroofing membrane formulation to promote bonding while still maintainingthe long term weathering characteristics of the roofing membrane. Forexample, polymer types may be blended in the TPV roofing membrane, suchas neoprene or a maleic anhydride grafted polymer, such as Exxelor fromExxonMobil. Possible polymer additives may include halogenated polymers,ethylene vinyl acetate, ethylene/acrylates, reactive olefins with maleicanhydride grafts or glycidyl methacrylate, styrene block polymers, andthermoplastic olefins. Still further, the various above noted sealantraw materials may also be modified with functional groups such asmalaeic anhydride, carboxylic acid, silanes, acrylates, methacrylate,and the like. Still further, other ingredients such as plasticizers,tackifying resins, antioxidants, UV stabilizers, fillers, pigments,adhesion promoters, catalysts, curatives, or the like, may be added tothe sealant and/or TPV roofing membrane to promote bonding therebetween.

Two general modes of promoting bonding by polymer sealant bondingadditives are contemplated with the roofing system. The first is by thepromotion of mechanical bonding between the sealant and roofingmembrane. For example, mechanical bonding promoting polymer sealantbonding additives may be introduced to the TPV roofing membrane materialthat modify the surface of the TPV roofing membrane material by makingthe surface receptive to the sealant. In particular embodiments, polymersealant bonding additives may be introduced having polar groups thatwill bond with polar groups in the sealant. As described below, asubstantially solid sealant containing EVA has increased bondingaffinity to a TPV roofing membrane modified with EVA, and to TPV roofingmembranes modified with ethylene/acrylate polymers and grafted polymers.Likewise, a substantially solid sealant containing SEBS has increasedbonding affinity to a TPV roofing membrane modified with SEBS, likelymainly through end block attraction. Alternative mechanical bondingpromoting polymer sealant bonding additives may act not by polar groups,but rather by a fusing reaction, In the case of a hot melt substantiallysolid sealant, which is applied by heating the substantially solidsealant to a temperature at which it will flow adequately, the heat fromthe melted substantially solid sealant may enable a mechanical bondingreaction between the sealant and TPV roofing membrane. For example, aheat melt substantially solid sealant containing TPO may have increasedbonding affinity to a TPV roofing membrane modified with TPO throughsuch a mechanical bonding in like manner to a heat welded bond of TPOmembranes.

The second contemplated mode of promoting bonding by polymer sealantbonding additives is through chemical reaction such as, for example, bya reaction between a maleic anhydride grafted polymer and a gylcidylmethacrylate grafted polymer. The maleic anhydride reacts with the epoxyring of the gylcidyl methacrylate at approximately 250 degreesFahrenheit. Applying a hot melt substantially solid sealant, which isapplied at a temperature of approximately 350 degrees Fahrenheit orgreater, may enable such a chemical reaction to take place. In theexample discussed below, the TPV roofing membrane is modified with themaleic anhydride grafted polymer and a hot melt substantially solidsealant includes the gylcidyl methacrylate grafted polymer. It should beappreciated, however, that the presence of the respective polymersealant bonding additives in the roofing membrane and substantiallysolid sealant could be switched. Additionally, in the example discussedbelow, the gylcidyl methacrylate grafted polymer is used in asubstantially solid sealant also containing EVA. Inclusion of gylcidylmethacrylate grafted polymer as a polymer sealant bonding additive mayalso be used with other hot melt sealants, such as hot melt sealantsincluding styrene block polymers and olefins. It should also beappreciated that alternative polymer sealant bonding additives may beemployed producing alternative chemical reaction type bonding other thanthe reaction of the maleic anhydride grafted polymer with the epoxy ringof the gylcidyl methacrylate grafted polymer.

The polymer sealant bonding additives may be introduced to the TPVroofing membrane at various stages in the production process for formingthe TPV roofing membrane depending on whether a functional group ispresent on the particular polymer sealant bonding additive beingintroduced that would react during the crosslinking of the rubber phaseof the TPV material. Polymer sealant bonding additives including afunctional group that would compete with the crosslinking rubber phasereaction would be introduced after the curing reaction has occurred.This may occur in a single pass operation if the TPV material productionequipment is of sufficient length. Alternatively, the TPV material maybe pelletized prior to a sheeting operation, in which case the polymersealant bonding additive and pelletized TPV material may be, forexample, combined in the extruder or at a calendar when processing thematerial into sheeting at a separate operation. Polymer sealant bondingadditives that do not interfere with the TPV material curing reactionmay be introduced during the initial mixing of the ingredients or afterthe curing process, including by combining with pelletized TPV materialwhen processing the material into sheeting.

Table 4 below provides examples of TPV roofing membranes modified withpolymer sealant bonding additives, with the amount of polymer sealantbonding additive shown by weight percentage. Also disclosed is the tradename and supplier of the particular polymer sealant bonding additiveused. The referenced base TPV is taken from the TPV formulationdescribed in Table 2.

TABLE 4 Polymer Sealant Additive Base TPV Bonding Additive Trade NameSupplier (Wt. %) (Wt. %) Base TPV No Additive — — — 100 Sample 1 styreneethylene Septon 8007 Kuraray Co. 9.1 90.9 butylene styrene Ltd. blockpolymer (SEBS) Sample 2 maleic anhydride Exxelor 1803 ExxonMobil 9.190.9 grafted polymer (MAH) Sample 3 acrylate modified Lotryl 30BA02Arkema Inc. 9.1 90.9 polymer (butyl acrylate) Sample 4 ethylene vinylEvatane 28-40 Arkema Inc. 9.1 90.9 acetate (EVA) Sample 5 thermoplasticHifax CA10A Basell 16.7  83.3 polyolefin (TPO)

Table 5 discloses certain material properties of the TPV roofingmembrane formulations of Samples 1-5 of Table 4, disclosing that theproperties are within the desired material parameters of Table 1.

TABLE 5 Tensile Strength Elongation (psi) (%) Tensile Set (%) Base TPV1443 510 6.8 Sample 1 1134 500 5.5 Sample 2 1496 475 7.3 Sample 3 1003350 7.8 Sample 4 1192 520 8.2 Sample 5 1229 450 7.7

Alternative suppliers, formulations, and polymer bonding additives maybe employed relative to those shown in Table 4. For example, SEBS blockpolymer may be supplied by Kraton Polymers LLC (trade name “Kraton”) orKurray Co. LTD, MAH grafted polymer may be supplied by Arkema (tradename “Orevec” and “Lotader”) or ExxonMobil (trade name “Exxelor”), andEVA may be supplied by ExxonMobil or Dupont (trade name “Elvax”), andTPO may be supplied by Basell (trade name “Hifax”), ExxonMobil (tradename “Exxact”) or Dow (trade name “Affinity”). Similarly, other acrylatemodified polymers may be used other than the butyl acrylate used in TPVroofing membrane Sample 3, such as methyl acrylate and ethyl hexylacrylate.

The polymer bonding additive in the TPV roofing membrane is likelyrequired to be supplied in the range of at least approximately 3% byweight of the TPV formulation in order to promote adhesion with thesealant. The upper limit of the polymer bonding additive being dictatedby the production of a TPV roofing membrane meeting the parameters ofTable 1.

Tables 6-9 disclose four substantially solid sealant formulations thatinclude polymer sealant bonding additives, with the polymer sealantbonding additives and other components shown by weight percentage. Alsodisclosed is the trade name and supplier of the particular polymersealant bonding additive and certain other components used.

TABLE 6 Sealant Sample 1 (SEBS Based Sealant) Component Trade NameSupplier Wt. % SEBS Septon 8007 Kurray Co. LTD. 10.3 Tackifying resinEastotac H130E Eastman 20.5 Polybutene TPC-1160 Texas Petroleum 28.2APAO Eastoflex P1023 Eastman 10.3 Antioxidant Iragnox 1010 Ciba 0.5Calicium carbonate 18.0 Titanium dioxide 6.1 Zinc oxide 6.1

TABLE 7 Sealant Sample 2 (EVA Based Sealant) Component Trade NameSupplier Wt. % ethylene propylene diene VN 722 ExxonMobil 8.0 terpolymer(EPDM) ethylene vinyl acetate (EVA) Evatane 33-400 Arkema 32.3 Parafinicoil Sunpar 150 Sunoco 5.4 Tackifying resin Escorez 5600 ExxonMobil 26.9Antioxidant Irganox 1010 Ciba 0.5 Calicium carbonate 24.2 Titaniumdioxide 2.7

TABLE 8 Sealant Sample 3 (EVA and gylcidyl methacrylate Based Sealant)Component Trade Name Supplier Wt. % gylcidyl methacrylate Lotader AX8300Arkema 10.9 (GMA—reactive PE) ethylene vinyl acetate (EVA) Evatane33-400 Arkema 31.3 Parafinic oil Sunpar 150 Sunoco 5.2 Tackifying resinEscorez 5600 ExxonMobil 26.0 Antioxidant Irganox 1010 Ciba 0.5 Caliciumcarbonate 23.5 Titanium dioxide 2.6

TABLE 9 Sealant Sample 4 (TPO Based Sealant) Component Trade NameSupplier Wt. % TPO Hifax Z108S Basell 24.9 Parafinic oil Sunpar 150Sunoco 16.6 Polybutene TPC 1160 Texas Petroleum 16.6 Tackifying resinEscorez 5400 ExxonMobil 21.6 Antioxidant Irganox 1010 Ciba 0.3 Caliciumcarbonate 18.3 Titanium dioxide 1.7

Sealant Samples 1-4 of Tables 6-9 are hot melt sealants that are 100%solid sealants. Substantially solid sealant Sample 1 of Table 6 includesa sealant SEBS block polymer bonding additive. Substantially solidsealant Sample 2 of Table 7 includes a sealant EVA polymer bondingadditive. Substantially solid sealant Sample 3 of Table 8 includessealant EVA and gylcidyl methacrylate (GMA) grafted polymer bondingadditives. Substantially solid sealant Sample 4 of Table 9 includes aTPO polymer bonding additive. Although not included, the sealantformulations could also contain UV light absorbers or stabilizers forenhancing long term weathering.

The TPV roofing membranes of Table 4 were tested for adhesion strengthand failure mode in connection with various of the substantially solidsealants of Tables 6-9. The sealants were applied at 350 degreesFahrenheit with fabric in the middle of the sample and the samples wereallowed to age seven days prior to a peel test being performed at 2inches per minute on a universal tester. The results of these peel testsare shown in Tables 10-13 below with comparison being made with the baseTPV roofing membrane formulation of Table 2 for reference. The indicatedpounds force is the resistive force of separation when peeled at therate of 2 inches per minute.

TABLE 10 Sealant Sample 1 - SEBS Based Sealant TPV Sample 1 Base TPVMembrane (SEBS Modified Membrane) lbs. force Failure mode lbs. forceFailure mode 1.18 100% cf 1.38 100% cf

TABLE 11 Sealant Sample 3 - EVA + GMA Based Sealant TPV Sample 2 BaseTPV Membrane (MAH Modified Membrane) lbs. force Failure mode lbs. forceFailure mode 6.60 80% af 10.98 100% cf

TABLE 12 Sealant Sample 2 - EVA Based Sealant TPV Sample 4 Base TPVMembrane (EVA Modified Membrane) lbs. force Failure mode lbs. forceFailure mode 7.14 50% af 8.25 100% cf

TABLE 13 Sealant Sample 4 - TPO Based Sealant TPV Sample 5 Base TPVMembrane (TPO Modified Membrane) lbs. force Failure mode lbs. forceFailure mode 7.20 100% cf 10.08 100% cf

The failure mode designation “cf” signifies a cohesive failure, which isa failure within the sealant. The failure mode designation “af”signifies an adhesive failure, which is a clean parting off the TPVroofing membrane. It is desirable to have a completely (100%) cohesivefailure with the highest load or force. In the testing indicated abovein Tables 10-13, the difference in the load when the mode of failure ofa substantially solid sealant is consistent between the membrane typesis related to the amount of material left on the sample or the depth ofresidue. As the depth of residue increases the load value increases.

As shown in Tables 10-13 above, bonding force between the sealantincluding a sealant polymer bonding additive and the TPV membraneimproved in each case with the TPV membrane including a TPV polymerbonding additive relative to the base TPV membrane.

Alternative combinations of polymer bonding additives or bases may beemployed to provide compatibly formulated TPV roofing membranes andsubstantially solid sealants to improve bonding there between. Forexample, the TPV polymer bonding additive may comprise anethylene-n-butyl acrylate, an ethylene-methyl acrylate, or an ethylene2-ethyl hexyl acrylate, with the sealant polymer bonding additivecomprising an ethylene vinyl acetate (EVA). Either the TPV or sealantpolymer bonding additive may comprise a gylcidyl methacrylate (GMA) withthe other of the TPV or sealant polymer bonding additive comprising amaleic anhydride grafted polymer (MAH).

The sealant polymer bonding additive in the sealant is likely requiredto be supplied in the range of at least approximately 3% by weight ofthe sealant formulation in order to promote adhesion with the TPVroofing membrane. The upper limit of the added sealant polymer bondingadditive being determined by the sealant properties of viscosity, flowduring application, such as when heated in the case of a hot meltsubstantially solid sealant, and flow during production of the sealant,as well as being non-tacky upon curing after application.

Referring again to FIGS. 1-3, TPV roofing membrane 24 is constructed asa unitary, finished product formed as a single layer and having athickness in the range of approximately 0.02 inches to 0.05 inches.However, alternative roofing membranes incorporating multiple layerswith at least one of the layers being a TPV membrane may be constructedand still function as intended within the scope of the presentinvention. Such alternative layers may be constructed or selected tohave alternative properties for a particular application characteristic,for example, slight changes between the formulations of the layers byadding different polymers may be employed for adhesion promotion orchemical resistance. Still further, a TPV roofing membrane may have anouter layer with improved weathering characteristics, such as by theinclusion of UV stabilizers, and an inner layer that is adapted foradherence to the roof of a mobile occupancy structure. Additionally oralternatively, the outer layer may be formulated to have particularcolor appearance characteristics. It should also be appreciated thatreinforcement layers, such as fabric reinforcement layers, may also beemployed with single or multi-ply TPV roofing membranes. Suchreinforcement layers may be utilized to provide still further supportand enhanced bonding surface.

As understood from FIGS. 4-6, alternative TPV roofing membranes, such asTPV roofing membranes 42, 42A, 44, 46, respectively, may be utilized.TPV roofing membrane 42 of FIG. 4 is a two-ply membrane in which bothlayers are formed as TPV membranes. Outer TPV membrane 48, for example,may have a thickness of approximately 0.005 inches to 0.045 inches andbe formulated as a weathering surface with UV stabilizers. Inner TPVmembrane 50, also by way of example, may have a thickness ofapproximately 0.005 inches to 0.045 inches and be formulated without UVstabilizers as a cost savings and function as a base layer to be adheredto the roof of the occupancy structure. Because of the TPV nature itcould also be adhered to a TPO or EPDM layer if so desired. As shown inFIG. 4A, a reinforcement layer or a fabric layer 49 may be sandwichedbetween outer and inner layers 48, 50. Such a fabric layer may beconstructed of a weft insert or woven material and function to preventTPV roofing membrane 42A from being over stretched during application toa roof of an occupancy structure. Still further, an alternativereinforcement layer or fabric layer may be disposed against the surfaceof inner layer that is to be affixed to the roof. Such a reinforcementlayer could be formed from a fleece, weft, woven, coated product, or thelike.

The roofing membrane shown in FIG. 5 illustrates an alternativetwo-layer TPV roofing membrane 44 having an outer TPV membrane layer 52and an inner fabric layer 54 adapted to be adhered to a roof of anoccupancy structure. The roofing membrane of FIG. 6 illustrates athree-layer TPV roofing membrane 46 having an outer TPV membrane layer56, a middle TPV membrane layer 58, and an inner fabric layer 60 adaptedto be adhered to a roof of an occupancy structure. The outer TPVmembrane layers 52, 56 of FIGS. 5 and 6, respectively, may, for example,incorporate UV stabilizers or UV screeners, such as pigments, forweathering resistance. It should be appreciated that the phrase “atleast one” TPV membrane may refer to a roofing membrane comprising asingle ply or layer.

The assembly of an occupancy structure with a TPV roofing membrane willnow be described with reference to FIGS. 7-11. FIG. 7 illustrates amobile occupancy structure 70 having a roof 72. Roof 72 is constructedto include trusses (not shown) over which oriented strand board (OSB) ismounted to form a substrate. Alternatively, luan board, plywood, or thelike, may be used in place of OSB. As shown in FIGS. 8 and 9, anadhesive 74 is applied to the roof 72. In the illustrated embodimentadhesive 74 is a water based adhesive and is applied by rolling to coverroof 72 (FIGS. 9 and 10). It should be appreciated, however, thatalternative adhesives and application methods may be utilized. FIG. 10is representative of a roll 76 of TPV roofing membrane 78 positionedadjacent to the occupancy structure 70 such that TPV roofing membrane 78may be pulled over and adhered to roof 72 by adhesive 74. Finally, asshown in FIG. 11, TPV roofing membrane 78 is smoothed and apertures orholes 80, 81 are cut into TPV roofing membrane 78 to enable roofingmembers, such as vent 84 and skylight 86, respectively, to extend fromroof 72 through TPV roofing membrane 78. As also shown in FIG. 11, theside flashing caps 88 and end flashing cap 90 roofing members areinstalled. A substantially solid sealant, not shown in FIGS. 7-11, isthen disposed about the roofing members as a sealant.

Although the substantially solid sealant is described above inconnection with a TPV roofing membrane it should be appreciated thatalternative roofing membranes, such as TPO and/or EPDM roofingmembranes, may be constructed to be compatible with substantially solidsealants as well. For example, particular formulations of TPO and/orEPDM roofing membranes on the one side and solid sealants on the othermay be formulated to be compatible to enable a sufficient bond to theroofing membrane and roof member while avoiding the need for theapplication of a primer to promote bonding. Such roofing systems wouldstill provide the advantages associated with elimination of solventbased sealants. For example, a substantially solid sealant including aTPO sealant polymer bonding additive should be compatible with a TPOroofing membrane.

Likewise, although the above described trailer 20 employs asubstantially solid sealant 38 with TPV roofing membrane 24, it shouldalso be appreciated that a conventional solvent based sealant may beemployed with a TPV roofing membrane, such as any of the TPV roofingmembranes 24, 42, 44, and 46 described above, with the TPV roofingmembrane still functioning as intended within the scope of the presentinvention. Such roofing systems would still provide the advantagesassociated with TPV roofing membranes. For example, a solvent basedsealant may be formulated to include a sealant polymer bonding additivepromoting adhesion with a TPV roofing membrane including a compatibleTPV polymer bonding additive.

Still further, although not shown, roof members may alternatively oradditionally be coated with a film that is compatible to the roofingmembrane such that they may be heat welded together, or the roofingmembrane material may be used in the manner of a welding rod or coil toform a seal. For example, the flange area on a vent could be coated witha material compatible for such bonding with a TPV roofing membrane.Alternatively, based on the compatibility of the roofing membrane withthe roof members, a thermoplastic roofing membrane may be heat weldableto or about the roof members without the requirement of a coating orfilm.

It should also be appreciated that while the above TPV roofing membrane24 is discussed and described in connection with trailer 20, that TPVroofing membrane 24 is well adapted for use with other occupancystructures to which roofing membranes are applied, includingrecreational vehicles, such as trailers and motor homes, mobile homes,and trailers for use as temporary offices and classrooms, or the like.

The TPV roofing membrane for roofing a mobile occupancy structure of thepresent invention has both elastic and plastic like properties whichprovide it with the flexibility of rubber and the processing of plastic.As such, the TPV roofing membrane is readily formed and applied tooccupancy structures having a roof with multiple curves or radiuses andis well adapted to provide good weathering characteristics. The TPVroofing membrane also provides sufficient strength and stretchcharacteristics such that it may be installed to an occupancy structurewithout the inclusion of a reinforcement layer. Still further, the TPVroofing membrane is heat weldable such that it may be readily reworkedif required and/or may be processed with heat sealing operations. Inaddition, the substantially solid sealant of the present inventionhaving at least approximately 90% or more solids may be used with theTPV roofing membrane or another roofing membrane, such as an EPDM or TPOroofing membrane. The substantially solid sealant includes a sealantpolymer bonding additive compatible with the roofing membrane, which mayinclude a roofing polymer bonding additive, to avoid the need forapplication of a primer to the roofing membrane while inhibitingshrinkage of the sealant during curing and the associated problems ofcracking and poor adhesion while promoting sufficient bonding of thesealant to both the disparate materials of the roofing membrane and roofmembers.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the presentinvention which is intended to be limited only by the scope of theappended claims, as interpreted according to the principles of patentlaw including the doctrine of equivalents.

The invention claimed is:
 1. A method of roofing an occupancy structure,said method comprising: providing a roofing membrane that comprises atleast one thermoplastic membrane layer, said roofing membrane providedfor bonding to the roof of an occupancy structure, where the occupancystructure includes a roof member that is at least partially constructedof a plastic material and extends above said roofing membrane when saidroofing membrane is applied to the occupancy structure; providing asubstantially solid hot melt thermoplastic sealant; heating saidsubstantially solid hot melt thermoplastic sealant to enable saidsubstantially solid hot melt thermoplastic sealant to flow; and applyinga layer of said substantially solid hot melt thermoplastic sealant to anexterior surface of said thermoplastic membrane layer and a plasticportion of the roof member after said roofing membrane is bonded to theroof to seal the joint between said roofing membrane and the roofmember.
 2. The method of claim 1, wherein said substantially solid hotmelt thermoplastic sealant comprises at least approximately 90 percentsolids by weight prior to use.
 3. The method of claim 2, wherein saidsubstantially solid hot melt thermoplastic sealant comprises at leastapproximately 100 percent solids by weight prior to use.
 4. The methodof claim 1, wherein said thermoplastic membrane layer comprises at least20 percent by weight of a plastic phase.
 5. The method of claim 4,wherein said plastic phase comprises polypropylene.
 6. The method ofclaim 1, wherein said substantially solid hot melt thermoplastic sealantincludes an ultraviolet (UV) light stabilizer.
 7. The method of claim 1,wherein said thermoplastic membrane layer includes a polymer bondingadditive, and wherein said polymer bonding additive interacts with saidsubstantially solid hot melt thermoplastic sealant during said applyinga layer of said substantially solid hot melt thermoplastic sealant to anexterior surface of said thermoplastic membrane layer and a plasticportion of the roof member to promote adhesion of said substantiallysolid hot melt thermoplastic sealant with said roofing membrane.
 8. Themethod of claim 7, wherein said substantially solid hot meltthermoplastic sealant includes a sealant polymer bonding additive, saidpolymer bonding additive and said sealant polymer bonding additiveinteracting to promote adhesion.
 9. The method of claim 8, wherein saidpolymer bonding additive and said sealant polymer bonding additivepromote adhesion by molecular interaction.
 10. The method of claim 1,wherein the occupancy structure includes a plurality of roof membersthat are at least partially constructed of a plastic material, andwherein said applying a layer of said substantially solid hot meltthermoplastic sealant to an exterior surface of said thermoplasticmembrane layer and a plastic portion of the roof member comprisesapplying a layer of said substantially solid hot melt thermoplasticsealant to an exterior surface of said thermoplastic membrane layer anda plastic portion of the roof members to seal the joints between saidroofing membrane and the roof members.
 11. The method of claim 1,wherein the roof member is completely constructed of a plastic material.12. The method of claim 1, wherein said thermoplastic membrane layercomprises a thermoplastic (TPV) membrane layer.
 13. A method of roofinga mobile occupancy structure, said method comprising: providing aroofing membrane that comprises at least one thermoplastic membranelayer, said roofing membrane provided for bonding to the roof of amobile occupancy structure, where the mobile occupancy structureincludes a roof member that is at least partially constructed of aplastic material and extends above said roofing membrane when saidroofing membrane is applied to the mobile occupancy structure; providinga substantially solid hot melt thermoplastic sealant, said substantiallysolid hot melt thermoplastic sealant comprising at least approximately90 percent solids by weight prior to use and including an ultraviolet(UV) light stabilizer; heating said substantially solid hot meltthermoplastic sealant to enable said substantially solid hot meltthermoplastic sealant to flow; and applying a layer of saidsubstantially solid hot melt thermoplastic sealant to an exteriorsurface of said thermoplastic membrane layer and a plastic portion ofthe roof member after said roofing membrane is bonded to the roof toseal the joint between said roofing membrane and the roof member. 14.The method of claim 13, wherein said substantially solid hot meltthermoplastic sealant comprises at least approximately 100 percentsolids by weight prior to use.
 15. The method of claim 13, wherein saidthermoplastic membrane layer comprises at least 20 percent by weight ofa plastic phase.
 16. The method of claim 15, wherein said plastic phasecomprises polypropylene.
 17. A method of roofing a mobile occupancystructure, said method comprising: providing a roofing membrane thatcomprises at least one thermoplastic membrane layer, said thermoplasticmembrane layer comprising at least 20 percent by weight of a plasticphase, said roofing membrane provided for bonding to the roof of amobile occupancy structure, where the mobile occupancy structureincludes a roof member that is at least partially constructed of aplastic material and extends above said roofing membrane when saidroofing membrane is applied to the mobile occupancy structure; providinga substantially solid hot melt thermoplastic sealant, said substantiallysolid hot melt thermoplastic sealant comprising at least approximately90 percent solids by weight prior to use; heating said substantiallysolid hot melt thermoplastic sealant to enable said substantially solidhot melt thermoplastic sealant to flow; and applying a layer of saidsubstantially solid hot melt thermoplastic sealant to an exteriorsurface of said thermoplastic membrane layer and a plastic portion ofthe roof member after said roofing membrane has been bonded to the roofto seal the joint between said roofing membrane and the roof member. 18.The method of claim 17, wherein said substantially solid hot meltthermoplastic sealant comprises at least approximately 100 percentsolids by weight prior to use.
 19. The method of claim 17, wherein saidsubstantially solid hot melt thermoplastic sealant includes anultraviolet (UV) light stabilizer.
 20. The method of claim 17, whereinsaid plastic phase comprises polypropylene.